Method of producing printing plate blocks



6., 1932. H. w. HACKER 1,872,572

METHOD OF PRODUCING PRINTING PLATE BLOCKS Filed April 20, 1931 ibrac W fiacizer Patented Aug. 16, 1932 UNITED STATES HORACE W. HACKER, OF LA GRANGE, ILLINOIS METHOD or rnontrcme lemma rnn'rn .B'LocKs Application filed April 20,

My invention relates to an improved method of producing printing plate blocks and particularly such blocks as are employed as a mounting for finished electrotypes, half tones and the like.

Heretofore mounting blocks of the type specified have been formed entirely of wood. In the use of an electrotype or half tone so mounted the greater part of the surface area of the mounting block is exposed to atmospheric humidity and frequent changes thereof, the result being that the mounting block will quickly swell, shrink or warp so that the combined block and plate is no longer possessed of the requisite accurate form and dimensions which will permit continued eflicient use of its associated plate. Attempts have been made to avoid this disadvantageous condition and its wasteful result by coating the surface of the block with waterproof material applied in liquid form but all such efforts have failed to prevent distortion and moreover are impracticable from the standpoint of time, bother and expense. In addition, the fact that applied plates protect the top surface of the block to a certain degree against atmospheric exposure while the bottom of the block remains freely exposed to the atmosphere produces an uneven condition of atmospheric contact between the top and bottom which induces warping of the block.

It is therefore my purpose to provide a novel method of producing printing plate blocks whereby the resulting blocks are so characterized that they will be protected from exposure to conditions conducive to warping, swelling and shrinking thereof and thus prevent deleterious deformation of any block so produced during the life of its associated printing plat-e. My improved method consists in cementing metal sheets to respective opposite faces of a wood slab to produce block stock in which said faces are hermetically sealed against atmospheric contact, and then cutting the stock thus formed into blocks of desired size. WVhere metal sheets which have a material thickness are employed then the wood slab is made of less thickness than the required blocks so that the application of the bodying my invention; .Figure 2, a perspective view showing an other adaptation of my invention; and

1931. Serial No. 531,535.

Where the metalsheets are ofnegligible thickness, such as metal foil, the wood slab would be made with substanthe accompanybroken away, of a printing plate block em Figure 3, a View similar to Figure 1 show-j ing still another adaptation of my invention.

.Inthe form of my. invention illustrated in Figure 1 my improved printing plate block is metal sheets will produce block stock of the required thickness.

shown as comprising a body 10 of the usual type of wood to whose top and bottomsurfaces I cement thin metal sheets 11 and 12, respectively, said sheets being relatively thin and having edge registration with the defining edges of the body 10. I have found in my experiments that zinc is a desirable metal of which to form the sheets 11 and 12 owing to its easy penetration by nails used in secure ing printing plates to their blocks and that such sheets secured in complete covering relation to the aforesaid surfaces of'the body I 10 with waterproof cement provide an effective hermetic seal which will eliminate contact of such surfaces with the atmosphere and effectively prevent warping, swelling or shrinking of the body 10. However,- any v other suitable sheet metal could be employed, the essential being that the top and bottom of the wood body 10 be metal surfaced. It will of course be understood that before the metal sheets 11 and 12 are applied the top and bottom of the body are planed so that the combined body 10 and sheets 11 and 12 have the proper depth, so that it is only necessary to apply the plate to the block, or if the block structure be of commercial'length and width,

then a section of desired size is cut therefrom i with no subsequent planing to establish proper relation and fit between the plate and block or to establish proper depth of the combined structure.

The adaptation shown in Figure 2 is similfll ,metically;. seaded against atmospheric-contact,

lar to that disclosed in Figure 1 with the added application of rubber tape 13 in covering relation to the side faces of the block so as to still further seal the block surfaces against atmospheric contact.

In Figure 3 I show the body 10 completely covered withrac metallic ioil 14,,such as tin or alilmimlm' foil; either}; which can-be readily cemented to the block in full covering relation to the latter.

I claim: a

1. The method of producing mounting blocks for printing plates which? consists-irrcementing metal sheetsto respective opposite faces of a Wood slab to provide block stock whereinroppositev faeesnof; the-stockx are; herand cutting the stock: thussformed; into blolzlwnofldesiredsizea 2 The -.1method-\, of; producing; mounting cblm@-;fon printinggplatesiwhichz consists in .fomning-mvwoodislab. ofi less thickness than the required blocks, cementingmetah'sheets 1 --,tooppositefaeesofitheslab tOiPL'Od'HCBTblOCk .sbeck ofiithe required thickness and .tmhenmetically seal said faces-:ofithe slabs against atimepheric -conta1ct','; and then .cu-tting L the stock thus:formed'intdblocks:oidesiredsize.

lmtestimnmyi=wheneofzlihereuntovafifirmy signature; 7 a

- a HQBAGE; 

